In the summer Bicycle Quarterly, there's an interview with Jean-Gualbert Faburel, one of the event organizers who says they're hoping to increase the registration limit to 8,000 for 2023. That's going to put even more pressure on Rambouillet's hotel and AirBnB inventory. I've tried booking a couple of AirBnBs in Rambouillet and SQY, my impression is that most of the AirBnB inventory isn't online yet for next August - the few I tried to book cancelled the reservation with messages that they weren't accepting bookings yet. Grabbed a spot in Versailles just to be safe, but may keep looking for something closer.